k8s pod注入环境变量

1. k8s-pod注入环境变量

• 变量值几种定义方式：

  • 自定义变量值
  • 变量值从Pod属性获取
  • 变量值从Secret、ConfigMap获取

• 参考yaml文件

  apiVersion: v1
  kind: Pod
  metadata:
    name: pod-envars
  spec:
    containers:
      - name: test
        image: busybox
        command: [ "sh", "-c", "sleep 36000"]
        env:
          - name: MY_NODE_NAME
            valueFrom:
              fieldRef:
                fieldPath: spec.nodeName
          - name: MY_POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: MY_POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
          - name: MY_POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          - name: ABC
            value: "123456"   # 自定义变量，后面要加 ""
  

2. 案例

• 编写一个pod-var.yaml配置文件

  [root@k8s-master yaml]# vim pod-var.yaml 
  [root@k8s-master yaml]# cat pod-var.yaml 
  apiVersion: v1
  kind: Pod
  metadata:
    name: pod-envars
  spec:
    containers:
      - name: test
        image: busybox
        command: [ "sh", "-c", "sleep 36000"]
        env:
          - name: MY_NODE_NAME
            valueFrom:
              fieldRef:
                fieldPath: spec.nodeName
          - name: MY_POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: MY_POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
          - name: MY_POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          - name: ABC
            value: "123456"   # 自定义变量，后面要加 ""
  

• 我们可以通过kubectl describe 查看一个pod或其他的详细信息

  [root@k8s-master yaml]#  kubectl  get pods
  NAME         READY   STATUS    RESTARTS   AGE
  probe-demo   1/1     Running   0          123m
                
  [root@k8s-master yaml]# kubectl describe pods probe-demo 
  Name:         probe-demo
  Namespace:    default
  Priority:     0
  Node:         k8s-node1/192.168.0.202
  Start Time:   Sun, 29 Nov 2020 14:44:23 +0800
  Labels:       test=liveness
  Annotations:  cni.projectcalico.org/podIP: 10.244.36.90/32
                cni.projectcalico.org/podIPs: 10.244.36.90/32
  Status:       Running
  IP:           10.244.36.90
  IPs:
    IP:  10.244.36.90
  Containers:
    web:
      Container ID:   docker://7e79b87e08f9df2097ac0d2363347dd00eb2e40636c22e0d176f670cc1937548
      Image:          nginx
      Image ID:       docker-pullable://nginx@sha256:6b1daa9462046581ac15be20277a7c75476283f969cb3a61c8725ec38d3b01c3
      Port:           80/TCP
      Host Port:      0/TCP
      State:          Running
        Started:      Sun, 29 Nov 2020 14:44:31 +0800
      Ready:          True
      Restart Count:  0
      Liveness:       tcp-socket :80 delay=0s timeout=1s period=10s #success=1 #failure=3
      Readiness:      tcp-socket :80 delay=30s timeout=1s period=10s #success=1 #failure=3
      Startup:        tcp-socket :80 delay=0s timeout=1s period=10s #success=1 #failure=3
      Environment:    <none>
      Mounts:
        /var/run/secrets/kubernetes.io/serviceaccount from default-token-8pppk (ro)
  Conditions:
    Type              Status
    Initialized       True 
    Ready             True 
    ContainersReady   True 
    PodScheduled      True 
  Volumes:
    default-token-8pppk:
      Type:        Secret (a volume populated by a Secret)
      SecretName:  default-token-8pppk
      Optional:    false
  QoS Class:       BestEffort
  Node-Selectors:  <none>
  Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                   node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
  Events:          <none>
  
  

• 启动服务

  [root@k8s-master yaml]# kubectl apply -f pod-var.yaml 
  pod/pod-envars created
  
  

• 进入容器看看，变量是否可以使用

  [root@k8s-master yaml]# kubectl exec -it  pod-envars  -- /bin/sh
  / # echo $MY_NODE_NAME
  k8s-node1
  / # echo $MY_POD_NAME
  pod-envars
  / # echo $MY_POD_IP
  10.244.36.91
  

• 小结：

  1. 在使用k8s 配置文件传入变量的时候，需要注意在变量上，整数或者字符串需要使用 单引号或双引号，否则或报错